Process for stabilizing photographic images with heat



United States Patent 3,301,678 PROCESS FOR STABILIZING PHOTOGRAPHIC IMAGES WITH HEAT Wilbert J. Humphlett, Dee Lynn Johnson, and Grant M. Haist, Rochester, N.Y., assignors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Filed May 28, 1964, Ser. No. 371,124 30 Claims. (Cl. 9661) This invention relates to a photographic process for stabilizing images, and more particularly, a photographic process for stabilizing photographic images with heat.

After an exposed photographic silver halide emulsion is developed and a silver image produced in the areas of exposure, the silver halide in the unexposed areas is conventionally removed as a soluble silver compound with hypo or other fixing solution if a permanent silver image is desired. Alternatively, the unexposed and undeveloped silver halide can be stabilized by reaction with a compound that forms a silver salt or complex that is relatively light in color and resistant to print-out. It would be convenient to have the fixing or image stabilizing agent as an integral part of the photographic element. However, usual fixing agents are not suitable for use in layers contiguous to photographic silver halide as they react with silver halide and render the emulsion useless for photographic purposes.

It would also be convenient to have a fixing or stabilizing agent as an integral part of the photographic element that can be readily activated by elevated temperatures but yet have substantial stability under temperatures of conventional use and storage. However, many precursors of fixing agents which may be compatible with photographic silver halide emulsions either cannot be activated at elevated temperatures at which conventional photographic silver halide emulsions can be subjected, or they are prematurely activated under temperatures of conventional use and storage.

It is thus an object of this invention to provide a new process for stabilizing photographic silver images.

It is another object of this invention to provide a new process for stabilizing silver images in photographic silver halide emulsions of photographic elements with stabilizing addenda which form integral parts of the photographic elements.

It is still another object of this invention to provide a new process for stabilizing residual silver halide in developed photographic elements which utilizes elevated temperatures to activate stabilizing addenda that are built-in to the photographic elements.

It is likewise an object of this invention to provide a novel method for processing photographic silver halide emulsions which obviates the necessity of a wet fixing bath.

These and other objects of the invention are accomplished by a process wherein is utilized a photographic element containing a silver halide emulsion and a sulfurcontaining compound contiguous to the silver halide and being either in the emulsion or in an adjacent contiguous overcoat or undercoat layer, the sulfur-containing compound breaking down or cleaving at elevated temperatures to form a compound that combines with the silver halide in the unexposed and undeveloped areas of the emulsion to form a silver mercaptide that is more stable than silver halide to light, atmosphere and ambient reducing conditions.

Suitable sulfur-containing compounds utilized in the present process have the following formulas:

Formula A Formula B R4 I] I IH o OR3-S 0 Formula C i RGHCH;CR7

SR Z

Formula D R10 R"CHC S-R12M In the above formulas: R, R R and R are each lower alkylene radicals having 1 to 5 carbon atoms including methylene, ethylene, propylene, butylene, isobutylene, and \amylene. R R R R and R are each hydrogen atoms, lower alkyl radicals having 1 to 5 carbon atoms or aryl radicals as described below for R and R'. R and R" are each aryl radicals such as phenyl and naphthyl, and typically include substituted aryl radicals as illustrated by the radical having the formula Q wherein D is typically a nitro radical, a hydroxy radical, a chloro radical, a bromo radical, a lower alkyl radical having 1 to 5 carbon atoms or a lower alkoxy radical wherein the alkyl moiety has 1"to' 5 carbon atoms. R and R are each cyano radicals, alkoxycarbonyl radicals wherein the .alkyl moiety has 1 to 5 carbon atoms or amido radicals.

(*ONHa) r X is an anion or acid residue'such'as chloride, bromide, nitrate, trichloroacetate, perchlorate, formate, acetate,

aminoacetate or the like. A is a hydroxy radical or a radical having the formula llv N-CO- 6 wherein R R R R R and R are each hydrogen atoms, lower alkyl radicals having 1 to carbon atoms or an aryl radical as described for R and R and X is an anion as described above. M and Z are each hydroxy radicals, carboxy radicals or amino radicals including primary (NH and secondary amino radicals, and more generally tertiary amino radicals such as morpholino, piperidino, pyrrolidino, and dialkyl amino wherein the alkyl moiety has 1 to 5 carbon atoms. Compounds of Formula C and Formula D above are commonly prepared as salts such as hydrochloride salts to facilitate purifications and to increase their water solubility to facilitate incorporation in photographic layers.

The subject sulfur-containing compounds function as precursors for image stabilizers in the present process and are stable and substantially inert in photographic silver halide emulsions in acidic or neutral media and under temperatures that prevail during conventional storage and use of photographic products. However, at elevated temperatures above about 200 F. the sulfur-containing derivatives of the invention cleave or convert to thiol compounds that form light-stable silver mercaptides having a solution pAg greater than about with the silver halide in the unexposed and undeveloped portions of the emulsion. In our process we heat the sulfur-containing derivatives to a temperature in the range of about 200 F. to 400 F. and preferably about 200 F. to 325 F. Such heating can be conveniently effected by contacting the photographic elementwith heated rollers or platens, with steam, infrared lamps or by any other suitable means for acquiring the desired temperature. The period of heating in the present process can be widely varied, such factors as the temperature and the ease of heat cleavability of the fixing or stabilizing agent precursor being features determining the duration of the heating step. Generally, however, such a heating period ranges from about 1 or 2 seconds to about a minute or more. One skilled in the art could readily ascertain optimum heating periods for the temperature and fixing or stabilizing precursor utilized.

The above-described sulfur-containing compounds are utilized in the present process at concentrations of at least one mole of addenda for each mole of silver halide in the emulsion. However, we preferably utilize molar excesses of the feature addenda to assure effective stabilization of the unexposed and undeveloped areas of the silver halide emulsion against print-out and image obliteration. Quite commonly, at least 5, or even 10, times as much stabilizing addenda is utilized than is required on a molar basis to stabilize the silver halide in the emulsion.

A small amount of moisture of at least the order of magnitude that is present in conventional photographic paper supports under typical room conditions (e.g., 25 C., 40% relative humidity) is catalytic to the heat cleaving of the present sulfur-containing compounds to useful image stabilizing compounds. Such small amounts of water can be residual Water from the developing process or the moisture can emanate from water present in the support or in the emulsion, such water being made available during the heating step of the present process. We have found that certain hygroscopic materials such as sodium sulfate, etc., in the subject photographic elements are especially useful sources of small amounts of water in the present process. Large amounts of water are not deleterious in the present process.

The sulfur-containing compounds used in the process of the invention can be used as described herein with various kinds of photographic emulsions. Such sulfur-containing compounds are useful with orthochromatic, panchromatic, infrared sensitive emulsions, as well as with X-ray and other nonoptically sensitized emulsions. Various silver salts can be usedas the sensitive salt such as silver bromide, silver iodide, silver chloride, or mixed silver halides such as silver chlorobromide or silver bromoiodide.

The subject sulfur-containing compounds can be added to or incorporated in photographic emulsions or layers by using any of the well-known techniques in emulsion making. For example, they can be dissolved in a suitable solvent and added as such, or they can be added in the form of a dispersion similar to the technique used to incorporate certain types of color-forming compounds (couplers) in a photographic emulsion. Techniques of this type are described in Jelley et al., US. Patent 2,322,027, issued June 15, 1943, and Fierke et al., US. Patent 2,801,171, issued July 30, 1957. Also, solvents or diluents which are miscible with water can be utilized. The solvent should be selected so that it has no harmful effect upon the emulsion in accordance with usual practice.

In the preparation of the silver halide dispersions employed for preparing silver halide emulsions used in the process of the invention, there can be employed as the dispersing agent for the silver halide, gelatin or some other :hydrophilic film-forming vehicle such as colloidal albumin, a cellulose derivative, or a synthetic resin, such as a polyvinyl compound. Gelatin is the preferred vehicle for the silver halide.

The emulsions utilized in preparing photographic elements used in the process of the invention can be coated on a wide variety of supports in accordance with usual practice. Typical suitable photographic supports include cellulose nitrate film, cellulose acetate film, polyvinyl acetal film, polystyrene film, polyethylene terephthlate film and related films of resinous materials, as well as glass, paper, wood, metals and others.

In carrying out the process of the invention, the photographic elements described above can be exposed and developed by any of the conventional methods and thereafter fixed or stabilized in accordance with the in-,

Vention by heating to an elevated temperature as described herein. The development can be efiected with conventional developers, including phenolic developing agents such as hydroquinone and N-methyl-p-aminophenol sulfate and such 3-pyrazolidone developers as lphenyl-3-pyrazolidone, 1-phenyl-4,4-dimethyl-3-pyrazolidone, 1-phenyl-2-acetyl-4-methyl-3-pyrazolidones and the like. The developer can be applied in a thin layer over the exposed photographic element, for example, an un developed and unexposed silver halide thereafter lightstabilized or fixed by bringing the photographic element in contact with a heated roller or platen, or the like. The present process can also be utilized in the processing of photographic silver halide emusions containing as corbic acid plus a 3-pyrazolidone developing agent that is activated at elevated temperatures by the process described in Belgian Patent 62 1, 608 granted Sept. 14., 1962. Other developers such as dimethyla minohexose reductone can be used in lieu of such combinations of ascorbic acid and 3-pyrazolidones. By merely heating such a latter described photographic element, both developing and image stabilization can be effected in that order as the developing process is finitely more rapid than the present image stabilization or fixing process. Also, acidic developing baths containing metallic ions such as vanadium and titanium ions can be used.

Examples 1 to 38 below describe the preparation of typical sulfur-containing addenda used in photographic elements processed in accordance with the inventionv Example 1.2-hydr0xyethylisothiuronium chloride Four moles of 2-chloroethanol and one mole of thiourea were placed in a one-liter flask and mechanically stirred at between 35 C. to 50 C. for hours. The resulting solution was cooled and a white crystalline product was precipitated with one liter of diethyl ether and recrystallized from ethanol, M.P. 109.5 to 110.5 C.- dec.

Example '2.-2-hydr0xyethylisothiuroniam nitrate To a solution of 900 ml. of acetone and 0.1 mole of silver nitrate was added 0.1 mole of Z-hydroxyethylisot-hiuronium chloride. A precipitate of silver chloride resulted but was redissolved upon heating. The mixture was decolorized with activated charcoal and concentrated to 100 ml., gradually replacing the methanol with 100 ml. of ethanol. The 2-hydroxyethylisothiuroniu'm nitrate was crystallized from ethanol, M.P. 128 C. dec.

Example 3.-2-hydroxyethylisothiuronium trichloroacetate From 0.5 mole of 2-hydroxyethylisothiuronium chloride and 0.06 mole of trichloroacetic acid converted to its potassium salt was obtained 10.9 g. (M.P. 124 C. dec.)

of 2-hydroxyethylisothiuronium triohloroacetate by the general method described in Example 2.

Example 4.2-hydroxyethylisothiuronium bromide Five moles each of 2-bromoethanol and thiourea were placed in a flask and mechanically stirred 1.5 hours in 1.5 liters of refluxing isopropanol. The reaction mixture was cooled, allowing the product to crystallize. After trituration with 2 liters of diethyl ether, 770 g. of 2-hydroxyethylisothiuronium bromide was obtained, M.P. 77.5 to 79 C.

Example 5.-3-hydr0xypr0pylisothiuronium bromide One mole of thiourea was dissolved in 150 ml. of refluxing isopropanol. To this solution, with mechanical stirring, was added one mole of 3-bromo-1-propanol in a stream, followed by one hour of refluxing. The reaction mixture was cooled, and after scratching and standing overnight, the white, crystaline 3 hydroxypropylisothiuronium bromide was obtained which was recrystallized from ethanol to give 190 g. of product, M.P. 95 to 96 C. dec.

Example 6.2-hydroxyethylisothiuronium v formate 25 grams (76 percent), M.P. 89 C. dec., of this salt was obtained from 0.2 mole of potassium formate and 0.2 mole of Z-hydroxyethylisothiuronium bromide by the general method described in Example 2.

Example 7.2-hydr0xyethylisothiuronium perchlorate This salt, 39 g. (92 percent), M.'P.-140 C., was prepared from 0.2 mole of silver perchlorate and 0.2 mole of 2-hydroxyethylisothiuronium bromide by the general method described in Example 2.

Example 8.Is0thiureid0acetic acid One mole each of chloroa-cetic acid sodium salt and thiourea and 500 ml. of water were placed in a flask and mechanically stirred 30 minutes on a steam bath.

A white, crystalline product was obtained upon cooling and was recrystallized from 600ml. of water to give 105 g. of isothioureidoacetic acid, M.P. 228 C. dec.

Example 9.2-isothiareid0pr0pi0nic acid To three moles of thiourea dissolved in one liter of water was added three moles of propiolactone in a stream in 30 minutes while the mixture was mechanically stirred. The reaction was midly exothermic, the final temperature was 75 C. Upon cooling and recrystallization from water, 430 grams, M.P. 168 to 170 C. dec., of 2-isothiureidopropionic acid was obtained.

Example 10.3-is0thiureidobutyric acid Two moles of thiourea, 2.5 moles of butyrolactone and 500 ml. of water were placed in a flask and vigorous- 1y refluxed and mechanically stirred for 60 hours, during which time a white, crystalline solid came out of solution. The solid was collected, triturated in 300 ml. of boiling water and dried to give 62 grams of 3-isothiureidobutyric acid, M.P. 219 C. dec.

Example 11.-2-hydr0xyethylisothiuroniam acetate 12 grams, M.P. 116 C. dec., of 2-hydroxyethylisothiuronium acetate was obtained byreacting 0.1 mole of silver acetate and 0.1 mole of 2-hydroxyethylisothiuronium bromide by the general method described in Example 2.

Example 12.2-hydr0xyethylisothiuronium' N-(p-hydroxyphenyl) -aminoacetate A 33 gram portion, M.P. 162 C. dec., of this salt was obtained by reacting 0.15 mole of N-(p-hydroxyphenyl)- aminoacetate converted to the potassium salt and 0.15 mole of 2-hydroxyethylisothiuronium chloride by the general method described in Example 2.

Example 13. ;3-(Z-morpholinoethylthio)-B- phenylpropiophenone hydrochloride A solution of 31.3 grams of benzalacetophenone (chalcone) and 22.1 grams of 2-morpholinoethanethiol in 150 ml. of ethyl alcohol was refluxed for one hour. Concentration of the reaction mixture and cooling resulted in precipitation of 48.8 grams of product which on recrystallization from methyl alcohol yielded 41.4 grams of product, M.P. 61.5 C. To a solution of 15 grams of product in anhydrous diethyl ether was added dry hydrogen chloride. The subject hydrochloride salt precipitated on standing, M.P. 149 C. on recrystallizing from methyl alcohol-ethyl acetate.

Example 14 The method of preparation described in Example 13 was repeated to prepare hydrochloride salts of adducts of 2-rnorpholinoethanethiol and several substituted chalcones in lieu of chalcone, the adducts having the formula -HCl Set out below are the melting points of the prepared hydrochloride salts designated by their R and R" substituents in the above formula.

Example 15.-;8-(Z-diethylaminoethylthio)-flphenylpropiophenone hydrochloride A solution of 0.1 mole of be'nzalacetophenone 0.11 mole of diethylaminoethanethiol in ml. of ethyl alcohol was refluxed for 30 minutes and the solvent removed in vacuo. The crude product amounted to 32.7 grams. The resulting adduct was dissolved in diethyl ether and hydrogen chloride added. Large crystals from the chilled solution on standing, M.P. C. when recrystallized'from ethyl acetate.

Example 16.,8-(3-diethylamino-Z-hydroxypropylthio)- 8-phenyl-p-methoxypropiophenone hydrochloride This adduct was formed from reaction of 3-diethylamino-2-hydroxypropanethiol and benzalacetophenone by a procedure similar to that of Example 14, M.P. 74 C.

Example 17.-/8-carboxymethylthiofi-phenylpropiiophenone A solution of 0.1 mole of benzalacetophenone and 0.15 mole of mercaptoacetic acid in 100 ml. of glacial acetic acid was refluxed for 15 minutes. The reaction mixture was cooled and diluted with water. The resulting crystalline product amounted to 24.7 grams, M.P. 129 C. when recrystallized from diethyl ether-ligroin.

Example 18 The method of preparation described in Example 17 was repeated to prepare adducts of mercaptoacetic acid and two substituted chalcones in lieu of benzalacetophenone (chalcone), the adduct having the formula l I II melting at 130 C., and the adduct having the formula SCI-Iz0 OH melting at 90 C.

Example 19.-Methyl a-carbomethoxy-p-(2- morpholinoethylthio-[i-phenylpropionate hydrochloride A solution of 0.1 mole of dimethyl benzalmalonate and 0.1 mole of 2-morpholinoethanethiol was refluxed in 200 ml. of ethyl alcohol for one hour. The solvent was removed under reduced pressure, the residual oil was dissolved in diethyl ether and hydrogen chloride was added. The resulting white solid was recrystallized from methyl alcohol-ethyl acetate, M.P. 166 C.

Example 20.Methyl a-carbomethoxy-B-(Z-morpholinoethylthio) -fl-(p-methoxypheriyl) propionate hydrochloride The method of preparation described in Example 19 was repeated with dimethyl p-methoxybenzalmalonate being utilized in lieu of dimethyl benzalmalonate to give the corresponding hydrochloride salt, M.P. 165 C.

Example 21.Ethyl a-carbethoxy-fl-(2-morpholinoethylthio)-,B-phenylpr0pionate hydrochloride The method of preparation described in Example 19 was repeated with diethyl benzalmalonate being utilized in lieu of dimethyl benzalmalonate to give the corresponding hydrochloride salt, M.P. 130 C.

Example 22.--Ethyl a-carbethoxy-fl-(2-morpholinoethylthio)-propi0nate hydrochloride Using the method described in Example 19, the reaction of diethyl methylenemalonate withv 2-morpholinoethanethiol followed by addtion of hydrogen chloride resulted in the subject adduct, M.P. 120 C.

Example 23.-2-ethylamz'noethylisothiuronium chloride Two moles each of thiourea (152 grams) and 2-chloroethylamine hydrochloride (288 grams) -were refluxed overnight in 1.3 liters of isopropanol. Recrystallization from methanol gave 300 grams (68 percent) of Z-ethylaminoethylisothiuronium chloride, M.P. 172 C.

Example 24.2-dimethylaminoethylisothiuronium chloride hydrochloride From the reaction of 1.5 moles of Z-dimethylaminoethyl chloride hydrochloride and thiourea in 0.5 liter of isopropanol, was obtained grams (39' percent) of 2-dimethylaminoethylisothiuronium chloride hydrochloride, M.P. to 182 C.

Example 25.2-hydroxypropylisothiuronium trichloroacetate Example 26.1,2-ethylenebis(isothiuronium bromide) Purchased from Aldrich Chemical Co. and recrystallized from methanol by precipitation into acetone.

Example 27.N-batylcarbamoyloxyethylisothiuronium chloride One mole (188 grams) of 2-chloroethyl-N-butylcarbamate and one mole (76 grams) of thiourea were refluxed overnight in 0.5 liter of isopropanol. Crystallization gave 242 grams (95 percent) of N-butylcarbam oyloxyethylisothiuronium chloride, M.P. 77 to 79 C. (one molecule, methanol of crystallization).

Several additional sulfur-containing compounds of the invention useful in forming light-stable silver mercaptides with unexposed and undeveloped silver halide in accordance with the invention can be prepared by reacting various thiols and unsaturated compounds, and the hydrochloride salt formed, by the general method described in Example 13. Examples 28 to 38 below set out the thiols and unsaturated compounds that are reacted.

Example 28.a-Nitrilo-;8-(Z-morpholin'oethylthio) B-phenylpropionitrile hydrochloride The thiol, 2-morpolinoethanethiol, is reacted with the unsaturated compound having the formula,

Example 29'.a-Nitrilo- 3-(Z-morpholinoethylthio)propionitrile hydrochloride The thio, 2-morpholinoethanethiol, is reacted with the unsaturated compound having the formula,

CHFC CN 2 Example 30.a-Carbethoxy-B- (2-m0rpholinoethylthio) 5-phenylpropi0nitrile hydrochloride The thiol, 2-rnorpholinoethanethiol, is reacted with the unsaturated compound having the formula,

Example 31.a-Carbethoxy-fi-(Z-morpholinoethylthio)propionitrile hydrochloride The thiol, 2-morpholinoethanethiol, is reacted with the unsaturated compound having the formula,

l CHz=( -COCH2CH3 9 Example 32.Etlzyl a-amido-fi-(Z-morpholinoethylthio)-/3-phenylp-r0pi0nate hydrochloride The thiol, 2-morpholinoethanethiol, is reacted with the unsaturated compound having the formula,

O CHzCH3 (JINHz 0 Example 33 .-Ethyl a-amido-fi-(2-m0rph0lin0- ethylthio) propionate hydrochloride The thiol, 2-morpholinoethanethiol, is reacted with the unsaturated compound having the formula,

COCH2CH CH2=O CNHB Example 34.Ethyl u-carbetIwxy-B-(Z-piperidinoethylthio)-fi-phenyl'propionate hydrochloride The thiol, 2-piperidinoethanethiol, is reacted with the unsaturated compound having the formula,

Example 35.-Ethyl a-carbethoxy-p-(Z-morpholinoethylthi0)-propi0nate hydrochloride The thiol, 2-morpholinoethanethiol, is reacted with the unsaturated compound having the formula,

0 orn=o do omoml Example 36.Methyl a-carbomethoxy-fi-(2-m0rpholinoethylthio)-pr0pionate hydrochloride The thiol, 2-morpholinoethanethiol, is reacted with the unsaturated compound having the formula,

0 CH2=O lOC a 2 Example 37 .Methyl a-carbomethoxy-p (S-diethylaminm 2hydr0xypropylmercapto)- B-phenylpr0pi0nate hydrochloride The thiol, 3-diethylamino-2-hydroxypropanethio, is reacted with the unsaturated compound having the formula,

0 -o1-r=o (300113 2 Example 38.M ethyl a-carbomethoxy-p-(3-diethylamino- 2-hydroxypropylmercapt0)propionate hydrochloride The thiol, 3-diethylamino-2-hydroxypropanethiol, is reacted With the unsaturatedcompound having the formula,

A wide variety of other sulfur-containing compounds :prepared by the general;methods described above can be utilized in the invention including the following:

10 (k) N-phenylcarbamoyloxyethylisothiuronium chloride, (1) Ethyl-a-carbethoxy-fi-(2-morpholinoethylthio) butyrate hydrochloride,

and the like.

Example 39 On a photographic paper support Was coated at a wet thickness of .005 inch a composition composed of 20 ml. water, 20 ml. of 10% gelatin and 3 grams of 2-hydroxyethylisothiuronium chloride. The coating was thereafter dried at about 25 C. Over the resulting layer was coated a light-sensitive layer having a thickness of .003 inch prepared by coating and drying at about 25 C. a composition composed of a 2 ml. portion of a silver halide emulsion, 20 ml. of Water and 20 ml. of 10% gelatin. The silver halide emulsion was a negative-type, medium speed, gelatino-silver bromoiodide emulsion containing one mole of silver halide per 880 grams of emulsion having 64 grams of gelatin. The silver halide emulsion was prepared by the method described by T rivelli and Smith in The Photographic Journal, vol. 79, p. 330331 (1939). The resulting photographic element was then exposed through a negative with white light, a thin layer of developer spread at a rate of one ml. per square foot over the photographic element and immediately thereafter the photographic element was passed for 15 seconds over a heated roller at a temperature of about 300 F. The unexposed and undeveloped areas of the resulting processed photographic element did not darken on exposure to roomlight and were substantially insensitive thereto without further stabilizing or fixing. The developer utilized had the following formula:

N-methyl-p-aminophenol sulfate 3.0 Sodium sulfite (anhydrous) 45.0 Hydroquinone 12.0 Sodium carbonate 80.0 Potassium bromide 2.0

Water to make one liter.

Example 40 A three ml. portion of the negative-type, medium speed, gelatino-silver bromoiodide emulsion described in Example 39 was added to 10 m1. of water, 10 ml. of 50% gluconic acid, 2 grams of 2-is'othiureidopropionic acid and 20 ml. of 10% gelatin. The resulting composition was coated on a baryto-coated photographic paper support at a wet thickness of .006 inch and .thereafter dried at about 25 C. The resulting photographic element was thereafter exposed through a negative and processed as described in Example 39 except that a roller temperature of about 250 F. was utilized. The unexposed and undeveloped areas of the resulting processed photographic element did not darken on exposure to roomlight and were substantially insensitive thereto without further stabilizing or fixing.

Example 41 lized. The unexposed and undeveloped areas of the -resulting processed photographic element did not darken on exposure to roomlight and were substantially insensitive thereto without further stabilizing or fixing.

Example 42 A 3.5 ml. portion of the negative-type, medium speed, gelatino-silver bromoiodide emulsion described in Example 39 was added to 15 ml. of water, 20 ml. of 10% gelatin, ml. of 7.5% saponin and 2 grams of ,B-(Z-diethylaminoethylthio) B-phenylpropiophenone hydrochloride. The resulting composition was coated on a cellulose acetate photographic film support at a wet thickness of .066 inch and thereafter dried at about 25 C. The resulting photographic element was then exposed through a negative with white light, a thin layer of developer as described in Example 39 spread thereover at a rate of one ml. per square foot, and immediately thereafter passed for 30 seconds over a heated roller at a temperature of about 200 F. The unexposed and undeveloped areas of the resulting processed photographic element did not darken on exposure to roomlight and were substantially insensitive thereto without further stabilizing or fixing. Similar results are obtained with a photographic element processed as described wherein the emulsion contains 2 grams of methyl a-carbomethoxy-fl-(2-rnorpholinoethylthio)-/3-phenylpropionate hydrochloride in lieu of the [3- (Z-diethylaminoethylthio) paphenylpropiophenone hydrochloride.

Example 43 The feature sulfur-containing compounds described in Examples 1 to 38 form light-stable silver mercaptides with unexposed and undeveloped silver halide when subjected to a temperature of about 250 F. for 15 seconds. The sulfur-containing emulsion addenda described in Examples 1 to 38 are combined in 2 gram portions with ml. of water, 10 ml. of 50% gluconic acid and 20 ml. of 10% gelatin. The resulting compositions are coated on barytacoated photographic paper supports at Wet thicknesses of .006 inch and thereafter dried at about 25 C. On exposing the resulting photographic element through a negative, spreading thereon a thin layer of the developer described in Example 39 at a rate of one ml. per square foot, and immediately thereafter passing the elements over a heated roller for a period of seconds, the unexposed and undeveloped areas of the resulting processed photographic elements are rendered substantially insensitive to roomlight.

Example 44 The process of the invention was effected by heating a photographic element containing both black-and-white developer and a sulfur-containing compound serving as an image-stabilizing agent. A photographic paper Was used as the support for the photographic element. A 3.5 ml. portion of the negative-type, medium speed, gelatino-silver bromoiodide described in Example 39 was combined with ml. of 10% gelatin, 2 grams of betaine, 5 grams of dimethylaminohexose reductone, and 2 grams of 8-(2- morpholinoethylthio) flaphenyl p-methoxypropiophenone hydrochloride dissolved in 16 ml. of water and 4 m1. of glacial acetic acid. The resulting emulsion was then coated on the paper support at a wet thickness of .006 inch and thereafter dried at about C. One-half of the resulting photographic element was flash exposed to white light, while the other half was protected from light. The back of the exposed photographic element was then pressed against the surface of a metal roller heated to 275 F. for a period of about 15 seconds. The unexposed area of the resulting processed photographic element did not substantially darken or print out on prolonged exposure to room light and was substantially insensitive thereto without further stabilizing or fixing. Similar results are obtained when 2 gram portions of the fea ture sulfur-containing compounds described in Examples 1 to 38 are utilized in lieu of the 2 grams of ,B-(Z-morpholinoethylthio p phenyl-p-methoxypropiophenone.

1 2 Example 45 The process of the invention was carried out with a photographic element containing both a developer and a sulfur-containing compound serving as an image stabilizing agent as described in Example 44 except 0.2 gram of 1-phenyl-3-pyrazolidone and 0.4 gram of ascorbic acid was utilized as the developer in lieu of the 0.5 gram of dimethylaminohexose reductone The unexposed area of the process photographic element did not substantially darken or print out on prolonged exposure to roomlight and was substantially insensitive thereto Without additional stabilizing or fixing.

Thus, in accordance with our invention a new and useful process for stabilizing photographic images is provided.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

We claim:

1. A substantially dry stabilization method which comprises heating, at a temperature in the range of about 200 F. to about 400 R, an exposed photographic element comprising a photographic silver halide emulsion, and con tiguous to said silver halide, at least about one mole per mole of said silver halide of a sulfur-containing compound which upon said heating forms a compound that combines with unexposed silver halide to form a silver mercaptide which is more stable to light than said silver halide.

2. The method of claim 1 wherein said sulfur-containing compound has a formula selected from the group consisting of h-R -Z h-R -M R1! wherein:

R, R R and R are each an al'kylene radical having 1 to 5 carbon atoms;

R R R, R and R are each selected from the group consisting of a hydrogen atom, an alkyl radical having 1 to 5 carbon atoms and an aryl radical;

R and R are each an aryl radical;

R and R are each selected from the group consisting of a cyano radical, a carbalkoxy radical wherein the alkyl moiety has 1 to 5 carbon atoms and an amido radical having the formula X is an anion;

M and Z are each selected from the group consisting of a hydroxy radical, a carboxy radical and an amino radical; and

A is a radical selected from the group consisting of (a) a hydroxyl radical, and (b) a radical having a formula selected from the group consisting of 13 wherein:

R R R R R and R are each selected from the group consisting of hydrogen atoms, alkyl radicals having 1 to carbon atoms and aryl radicals.

' 3. The method of claim 1 wherein said sulfur-containing compound has the formula wherein R'is an alkylene radical having 1 to 5 carbon atoms and X is an anion.

4. The method of claim 1 wherein said sulfur-containing compound has the formula wherein R is an alkylene radical having 1 to 5 carbon atoms.

5. The method of claim 1 wherein said sulfur-containing compound has the formula wherein:

R and R are each aryl radicals; R is an alkylene radical having 1 to 5 carbon atoms;

and Z is selected from the group consisting of a hydroxyl radical, a carboxy radical and an amino radical. 6. The method of claim 1 wherein said sulfur-containing compound has the formula wherein:

R is an aryl radical; R and R are each a carbalkoxy radical wherein the alkyl moiety has 1 to 5 carbon atoms; R is an alkylene radical having 1 to 5 carbon atoms;

and M is selected from the group consisting of a hydroxy radical, a carboxy radical and an amino radical. 7. The method of claim 1 wherein said sulfur-containing compound has the formula wherein:

R is an alkyl radical having 1 to 5 carbon atoms; R is an alkylene radical having 1 to 5 carbon atoms;

and X is an anion. 8. The method of claim 1 wherein said sulfur-containing compound has the formula R and R are each an alkyl radical having 1 to 5 carbon atoms; v

R is an alkylene radical having 1 to 5 carbon atoms;

and

X is an anion.

9. The method of claim 1 wherein said sulfur-containing compound has the formula NH2 9 RNH-R S--O wherein:

R is an alkyl radical having 1 to 5 carbon atoms;

R is an alkylene radical having 1 to 5 carbon atoms;

and

X is an anion.

10. The method of claim 1 wherein said sulfur-containing compound is present in said silver halide emulsion and has the formula wherein:

R is an alkylene radical having 1 to 5 carbon atoms; and

X is an anion; said heating being performed at a temperature in the range of about 200 F. to about 325 F.

-11. The method of claim 10 wherein said sulfur-containing compound is 2-hydroxyethylisothiuronium chloride.

12. The method of claim 10 wherein said sulfur-containing compoundis 2-hydroxyethylis-othiuronium trichlor-oacetate.

13. The method of claim 10 wherein said sulfur-com taining compound is 2-hy'droXyp-ropylisothiuronium trichlor oacetate.

14. The method of claim 1 wherein said sulfur-containing compound is present in said silver halide emulsion and has the formula wherein R is an alkylene radical having 1 to 5 car-hon atoms; said heating being performed at a temperature in the range of about 200 F. to about 325 F.

15. The method of claim '14 wherein said sulfur-containing compound is 2-isothiureidopropionic acid.

16. The method of claim 1 wherein said sulfur-containing compound is present in said silver halide emulsion and has the formula wherein:

A is a phenyl radical;

R is an alkylene radical having 1 to 5 carbon atoms;

and

Z is a tertiary amino radical; said heating being performed at a temperature in the range of about 200 F. to about 325 F.

17. The method of claim 16 wherein said sulfur-containing compound is fl-(2-morpholinoethylthio)- 3-phenyl propiophenone hydrochloride.

18. The method of claim 16 wherein said sulfur-containing compound is ,3-(2-diethylaminoethylthio)-fi-phenyllpropiophenone hydrochloride.

19. The method of claim 1 wherein said sulfur-containing compound is present in said silver halide emulsion and has the formula wherein: I

A is a phenyl radical; and V R is an alkylene radical having 1 to carbon atoms; said heating being performed at a temperature in the range of about 200 F. to about 325 F.

20. The method of claim 1 wherein said sulfur-containing compound is present in said silver halide emulsion and has the formula wherein:

A is a phenyl radical; and

R is an alkylene radical having 1 to 5 carbon atoms; said heating being performed at a temperature in the range of about 200 F. to about 325 F.

21. The method of claim 1 wherein said sulfur-containing compound is present in said silver halide emulsion and has the formula R .is a phenyl radical;

R and R are each a carbalkoxy radical :wherein the alkyl moiety has 1 to 5 carbon atoms;

R is an alkylene radical having 1 to 5 carbon atoms;

and

M is a tertiary amino radical;

said heating being performed at a temperature in the range of about 200 F. to about 325 F.

22. The method of claim 21 wherein said sulfur-containing compound is methyl-a-carbomethoXy-B-(2 morpholinoethylthio)-,B-phenylpropionate hydrochloride.

23. The method of claim 1 wherein said photographic element contains an incorporated developer.

24. The method of claim 23 wherein said developer is heat-activata'ble.

25. The method of claim 24 wherein said developer is dimethyla-minohexose reductone.

26. The method of claim 24 wherein said developer is I-phenyl-3-pyrazolidone and ascorbic acid.

27. The method of claim 2 wherein said photographic element contains an incorporated developer.

28. The method of claim 27 wherein said developer is heat-activatable.

29. The method of claim 28 wherein said developer is dimethylaminoheXos-e reductone.

30. The method of claim 28 wherein said developer is 1-phenyl-3-pyrazolidone and ascorbic acid.

References Cited by the Examiner UNITED STATES PATENTS 3,088,824 5/1963 Jacobs 9663 3,140,178 7/1964 Herz et a1 96-61 3,189,453 6/1965 Herz et a1 9661 3,220,839 11/1965 Herz et a1 9661 NORMAN G. TORCHIN, Primary Examiner.

C. E. DAVIS, Assistant Examiner. 

1. A SUBSTANTIALLY DRY STABILIZATION METHOD WHICH COMPRISES HEATING, AT A TEMPERATURE IN THE RANGE OF ABOUT 200* F. TO ABOUT 400*F., AN EXPOSED PHOTOGRAPHIC ELEMENT COMPRISING A PHOTOGRAPHIC SILIVER HALIDE EMULSION, AND CONTIGUOUS TO SAID SILVER HALIDE, AT LEAST ABOUT ONE MOLE PER MOLE OF SAID SILVER HALIDE OF A SULFUR-CONTAINING COMPOUND WHICH UPON SAID HEATINGS FORMS A COMPOUND THAT COMBINES WITH UNEXPOSED SILVER HALIDE TO FORM A SILVER MERCAPTIDE WHICH IS MORE STABLE TO LIGHT THAN SAID SILVER HALIDE. 